Process for improving the dyeability of polymeric material



Uie at This invention relates to the dyeing of fibers, yarns, fabrics and other shaped articles substantially consisting of polymers containing nitrile groups, as defined hereinafter.

Though polyacrylonitrile fibers possess outstanding properties, yet the expansion of their technical application is strongly limited by the difiiculties which arise when dyeing these fibers and by the tendency of these fibers to take up static electricity.

In order to increase the afi'lnity for dyes, especially for acid dyes, of these fibers, it has been proposed to prepare copolymers, to fix the dyestufi with an intermediate copper atom or to alter the surface of the fibers by chemical reactions.

In the copolymerization, monomers with basic groups are preferred. Fibers consisting of such copolymers can indeed more easily be dyed. They are, however, less strong and their melting point lies considerably lower than that of the pure polyacrylonitrile fibers.

One of the most successful known methods in dyeing polyacrylonitrile fibers with acid dyes is the cuprous ion technique which consists in dyeing these fibers in the presence of cuprous ions (Chem. Eng. News 28, 4268 (1950) According to Wall, 3'. Textile Inst. 45, 238/271 (June 1954), the application of this process on a technical scale appears to cause undesirable difiiculties.

Recently, the possibility of dyeing acrylonitrile fibers manufactured from an acrylonitrile copolymer with a limited number of new cationic dyes was announced.

Treatments which superficially change the formed fibers by chemical reaction are for instance: saponification (H. Rein, Angew. Chem. 60 (1948), 159/161), and treatment with organic amines (British Patent No. 700,172) in the presence of sulphonic acid (British Patent No. 712,235) or other mineral substances with acid character.

A process enabling the improvement of the dyeability of fibers and comprising the reaction of hydroxylamine i on these polymers at a pH between 7 to 10 or higher is claimed in US. Patent No. 2,792,276.

It is an object of the present invention to improve the properties, especially the dyeability, of polymers containing nitrile groups.

Another object is the manufacture of White shaped articles consisting substantially of polymers containing acrylonitrile units with improved dyeability.

Still another object is the provision of a process for dyeing polyacrylonitrile fibrous material.

Other objects and advantages of the invention will appear as the description proceeds or will be apparent to those skilled in the art.

I have found that the afiinity for dyestufis of shaped articles comprising polymers containing nitrile groups,-

which have been treated with hydroxylamine, may fur- "ice ther be increased by a treatment with an aqueous solution of an aliphatic polyamine.

It is a particular advantage of this process that the affinity for dyes is substantially improved while at the same time the amount of hydroxylamine needed is de creased.

The present invention particularly relates to shaped articles as, for instance, powders, films, fibers, yarns and fabrics, consisting of polymers containing nitrile groups. The latter comprise polymers or copolymers, including graft and block copolymers, of acrylonitrile, methacrylonitrile and vinylidene cyanide, and they comprise also cyanoethylated polymers, in the first instance cyanoethylated cellulose, and mixtures of the above polymers with other polymers.

Although especially valuable in the dyeing of polyacrylouitrile fibers which are diflicultly dyeable otherwise, that is, stretched fibers consisting substantially of acrylonitrile homopolymers or of copolymers with high acrylonitrile content or of completely cyanoethylated polymers, the process may also be applied successfully to copolymers containing less than 50 percent acrylonitrile units. Although the present invention is especially concerned with the treatment of polyacrylonitrile polymers with an aqueous hydroxylamine solution it must be pointed out that the hydroxylamine treatment may also be carried out in alcoholic medium or even by treating the polymers in solution with hydroxylamine.

The degree of conversion needed in order to obtain fibers with very good dyeability may vary within wide limits; in some extreme cases a degree of conversion of 10% may be desirable, but in most cases the optimum is about 0.5-5%. The degree of conversion is defined as the ratio:

Weight of polymer converted assuming that the polymer consists exclusively of acrylonitrile and that 1 CN group reacts with l NH OH molecule.

The improved dyeability of the fibers treated with hydroxylamine seems to be due to the'primary formation of amidoxime groups which are then converted into hydroxamic acid groups.

Since hydroxylamine is too unstable to be available commercially I generally employ hydroxylamine salts of inorganic or organic acids from which the free base may be liberated WhOllY or partially at once or stepwise by addition of alkaline substances. However, it is important to note that hydroxylamine salts, being salts of weak bases, are substantially hydrolyzed and the amount of hyclroxylamine liberated in this way enables the reaction to set in Without liberating the hydroxylamine from its salts by addition of strong bases.

In the practice of the invention the hydroxylamine treatment may be carried out over practically the 'whole pH range, preferably between 2 and 10.

By polyarnines according to the present invention are meant substances having in their molecule at least two NH groups as well as their derivatives containing at least one amino group capable of being acylated. As illustrative examples of such amines may be mentioned: diaminoethane, 1,2-diaminopropane, 1,3-diaminopropane, 1,4-diaminobutane, 1,5 diaminopentane, 1,6 diarnino- 3 hexane, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, aminoethylethanolarriine, diethylaminoeth-ylamine.

Although it is considered as essential that the nitrile group has reacted with hydroxylarnine before the reaction between the thus formed reaction product and the polyamine takes place, the polyamine may be added to the reaction medium simultaneously with the by droxylamine. If desired, this step may include the addition of the dyestuif. f 7

The extent of the reaction with polyarnines is not critical but isseems that the proportion of 1 molecule of the polyamine for 1 amidoxime group of hydroxamic acid roup is the upper limit. 7

The reaction temperature for both the hydroxylarnine aiid polyamine treatments may vary Within wide limits. Conveniently both the treatments and dyeing are.ef-

I fectiiated near' the boiling point of the medium but the chemical treatments may be carried out at' temperatures from 50 C. to 125 0., preferably between 75 and 105 C. Also the dyeing operation may be carried out between these temperature limits, conveniently between 90 C. and the boiling point of theb'ath; if desired, the different operations may be carried out under pressure at higher temperatures.

' In practicing the invention fibrous material may be treated in a bath or the material may be part of a close circuit wherein the liquid is pumped through a bed of iibers. Alternatively the treat-merit with hydroxylamine and with polyamine's may also be applied immediately after spinning. V v

The discoloration which appears during the treatment of the fibers with polyamines may be removed by a treatment with diluted aqueous solution of strong acids such as sulphuric acid, hydrochloric acid, phosphoric acid, oxalic and malei'c acid. This treatment likewise involves an increase of the heat stability.

The fibers improved according, to the present invention may be dyed with a wide variety of dyes'belonging to difierent classes including acid, direct, disperse, vat, metalliz'able and metal complex dyes, also mixtures of dyes may be used. Although the aflinity for cationic dyes seems notto be increased, yet the fibers remain dyeable with these dyes. Also the Cuprous ion technique. may be used. Likewise noncolored substances, for example clearing and finishing agents, may be fi'ried on the fibrous material.

Normally, the reaction with hydroxylamine and with polyamines will be followed by the dyeing operation, but both may also be carried out in the same bath without changing the main liquid, simply by altering the com-'- position to the end in view. Preferablythe dyeing is carried out in an acid medium which may be obtained by addition of inorganic or of organic acid; In the difierent dyeing operations, dyeing assistants, relustering agents and buffering mixtures may be used.

The present invention can be put into practice in any known dyeing process including printing, Although it is the purpose to improve the afiinity for dyes, it is also accompanied by a greater water-absorption which considerably diminishes the receptivity for static electricity.

The following examples illustrate the present invention without, however,limiting the scope thereof:

. EXAMPLE 1' 100 g. polyacrylonitrile powder (obtained by emulsion polymerization) are boiled for 2 /2 hours in a solution consisting of 750' ml. water and 5 g. hydroxylaminesulphate (sample A). pH of the solution before the treatment: 3.7, after the treatment: 5.0. i

- Taking into aecount the quantity of hydroxylamine used, the degree of conversion amounts to 2.5%.

1 5 lg. samples of sample A are boiled for 1 hour in 50 ml. of a 1% aqueous solution of ethylene diamine (sample' B), hexamethylene diamine (sample C), and diet-byl- EXAMPLE 2 100 g. polyacrylonitrile powder as in Example 1 are boiled for /2 hour in 800 ml. of an aqueous solution containing 5 g. hydroxylami-nesulphate and 0.5 g. NaOH (this quantity of NaOH suffices to liberate 20% of the hydroxylamine). pH of the solution before the treatment: 5.4;after the treatment? 5.0. The degree of conversion amounts to 2.7%.

10 g. samples of the washed powder (A) are boiled for 1 hour in a 1% aqueous solution of ethylenediamine (sample B), hexamethylenediamine (sample C) and diethylaminoetliylamine (sample D). By boiling a sample for 1 hour in H 50 N/2 the yellow discoloration is completely removed. Next the samples A, B, C and D are boiled for /2 hour in a dye bath containing 0.2% Fast Red A.V. (CI. 15620) in H 30 N/l0. The dye uptake amounts to: 5% for sample A, 16% for sample B, and 14% 'for samples C and D.

EXAMPLE 3 1100 g. polyacrylonitrile as in Example 1 are treated for 2 hours with 1000 ml. of an aqueous solution containing 10 g. hydroxylaminesulphate and 4 g. NaOH (this quantity of NaOH is sufiicient to liberate 80% of the hydroxylamine)- pH before treatment: 6.7; after the treatment: 8.5.

After washing and-drying the powder (A) is slightly yellow colored. The color disappears by boiling it for V2 hour in H 504 N (sample B).

10 g. of powder B are'boiled for /2 hour in 100 ml. of a 3% aqueous diethylaminoethylamine solution (sample C).

10 g. of powder A are boiled for /2 hour in 100 ml. of a 3% aqueous triethylenetetramine solution (sample D).

10 g. of powder A are boiled for /2 hour in 100 ml. of a 3% aqueous ethylenediamine solution (sample B).

The difierent samplesare then dyed in the same dye bath consisting of 0.2% Fast Red A.V. (CI. 15620) in H 50, N/lO. V

The dye uptake amounts to: 10% for A and B, 20% for C, 30% for D and 40% for E.

EXAMPLE 4 i '10 g. polyacrylonitrile staple fibers (manufactured by Cassella) are boiled for /2 hour in a solution containing 0.5 g. of hydroxylamine hydrochloride, 0.32 g. anhydrous sodium carbonate and 150 ml. water. Thefibers are then thoroughly washed. After removing the excess of water they are boiled for /2 hour with an aqueous diethylaminoethylamine 2% solution. Next, they are rinsed again and pressed out. They possess a yellow color.

A small sample of these fibers is boiled in an aqueous oxalic acid'5% solution and then they become practically colorless. The remainder of the sample is boiled for /i hour with an aqueous Black Tetracide N.B.A.

(CI. 20740) 5% solution in HgsO /N. After boiling the fibers in water black colored fibers with good color stability are obtained.

EXAMPLE 5 l V V g. Orlon 42 (a copolymer mainly consisting of acrylonitrile manufactured by Du. Pont de Nemours) staple fibers are boiled up in an aqueous solution of a Wetting agent, rinsed and centrifuged.- Then the fibers are treated wih an aqueous solution consisting of 1250 ml. water, 5 g. hydroxylaminesulphate and 1.6 g. anhydrous sodium carbonate. The quantity of sodium carbonate sufiices to liberate 45% of the hydroxylamine. Next the fibers are boiled for '1 hour in 1 liter 0.5% aqueous'soluticn of diethylaminoethylamine. The Slightly yellow"discoloration of the fibers may be removed by treating them for 5 minutes with a 5% oxalic acid solution. -If-insteadof' this last treatment a 5 g. sample of the fibers is boiled for 1 hour in a solution containing 150 ml. water, 0.5 ml. formic acid and 0.25 ml. Calcocid M 9863, black dyeings are obtained.

' EXAMPLE 6 EXAMPLE 7 g. polyacrylonitrile staple fibers (manufactured by Cassella) are treated for 1 hour at 90 C. with a solu tion composed of 1 20 cm. of demineralized water, 0.3 g. hydroxylaminesulphate, 0.2 g. of ethylenediamine and 0.14 g. of NaOH. After adding cm. H SO /N and 0.5 g. Neolan Yellow (CI. 19010), the mixture is boiled for /2 hour. The fibers are deeply yellow colored.

EXAMPLE 8 10 g. Darlan (registered trademark for a copolymer mainly consisting of vinylidene cyanide manufactured by B. F. Goodrich) staple fibers are boiled for 30 minutes in a solution composed of 125 ml. water, 1 g. hydroxylaminesulphate and 0.45 g. NaOH. After adding2 m1. of ethylenediamine solution 70% the mixture is boiled for 30 minutes. Afterwards the pH is brought to 2 by adding sulphuric acid; then 0.25 g. Fast Red AV (C.'I. No. 176) is added and the mixture is further boiled for 30 minutes. Now the bath is practically exhausted.

Similarly dyeings were carried out with Anthraquinone Blue SWF (C.-I. 62055), Astrazon Red 6 B (C. I. 48020), Cibalan Scarlet GL (CJI. 1100), Indanthren Scarlet R (CI. 71140), Duranol Blue Green B 300 (C1. 62500).

EXAMPLE 9 This example is an alternative of Example 8 and is characterized thereby that the ethylenediamine and the hydroxylamine are added together from the beginning of the reaction. After this treatment the solution is acidified, whereafter Black Tetracide NBA (Cl. 20740) (an acid dyestufi manufactured by Soc. Carbochimique de Tertre) is added and further boiled for /2 hour.

The fibers are homogeneously black dyed.

EXAMPLE 10 10 g. Orlon-42 staple fibers (registered trademark of Du Pont de Nemours for staple fibers from a copolymer mainly consisting of acrylonitrile) are boiled for minutes in a solution composed of: 150 ml. water, 0.3 g. hydroxylamine sulphate (3% on the weight of fibers) and 0.14 g. NaOH (sufficient to liberate 95% hydroxylamine).

Next 1 g. diethylaminoethylamine is added to this solution and the mixture is again boiled for 20 minutes.

Finally, 1 g. Blue Formalan 26 (trade name for metal complex dyestufi manufactured by the Soc. Carbochimique de Tertre) and such a quantity of sulphuric acid whereby the pH of the solution is brought at about 3 are added to the bath.

After 20 minutes boiling, the fibers are clearly blue colored.

EXAMPLE 11 100 g. polyacrylonitrile monofilaments are treated during 15 minutes in a 1% Hostapon T (registered trademark for a wetting agent consisting of oleyl methyl tauride sodium salt manufactured by Farbwerke Hoechst,

' Germany) at 95-100 C., Washed and centrifuged (sample A).

Part of sample A, above, is treated for 3 hours at 90-95 C. in a solution consisting of 1500-ml. water, 5 g. hydroxylaminesulphate' and 2.2 g. NaOH (the quantity of NaOH suffices to neutralize 90% of the hydroxylamine) (sample B).

pH of this solution before treatment, 6.6; after treatment, 7.7; degree of conversion, 3%. The fibers are rinsed and centrifuged.

To the fibers from sample A and sample B are then applied the following treatments:

(a) No further treatment;

(b) Boiled for 1 hour in H N;

(c) Boiled for 1 hour in 1% ethylenediamine (E.D.); (d) Treatment c and treatment b;

(e) Treatment b and treatment c.

The different samples are then dyed in a dyebath consisting of 0.2% Fast Red AV (CI. 15620) in H 80 N/ 10. The dye uptakes are summarized in Table I.

Table I.Dye Uptake of Treated Fibers Treatment Sample A Sample B 0.1 0. 7 O 0. 1 0. 8 0.1 1. 5 2. 0 (e) HzSO4-I-E.D 0 1 5. 0

From these results it appears that:

(1) The treatments (a to e) are Without influence if applied to fibers not treated with hydroxylamine (sam- P (2) The dye uptake is increased if the fibers are treated in the indicated order,

(3) The H 80 treatment is practically without influence (compare sample B, a and b),

(4) The ethylenediamine treatment increases the uptake from 0.7 to 1.5% (compare sample B, a and c),

(5) The combined H 80 and ethylenediamine treatment increases the dye uptake from 0.7 to 5%.

Although not effeotuated quantitatively, it appears that the fibers (sample B, c) are perfectly dyed with Neolan Yellow (CI. 19010).

This application is a continuation-in-part of my application Serial No. 573,595, filed March 26, 1956, and since abandoned.

Iclaim:

1. Process for improving the dyeability of shaped articles formed from a polymeric substance selected from the group consisting of cyanoethylated cellulose, polyacrylonitrile, polymethacrylonitrile, polyvinylidene cyanide, copolymers mainly consisting essentially of acrylonitrile and copolymers mainly consisting essentially of vinylidene cyanide, which comprise the steps of (1) treating said articles for /2 to 2 /2 hours in a solution containing free hydroxylamine in a concentration between 0.12 and 0.4% and (2) after the hydroxylamine treatment to obtain from about 0.5 to 10% conversion of the nitrile groups in said article, further treatment of said article with a 0.16 to 3% aqueous solution of ethylenediamine at 50-125 C. for from /2 to 3 /2 hours.

2. Process for improving the dyeability of shaped articles according to claim 1, wherein said solution containing free hydroxylamine is obtained by adding an alkaline substance to a solution of a hydroxylamine salt.

3. Process for improving the dyeability of shaped articles according to claim 1 wherein after treating said articles with said aqueous solution containing free hydroxylamine and subsequently with said aqueous solution of '2', t.. ..8' ethylene diamine, said rshaped articles are treated with 2 ,792,276 Kaupin May 14; 1957 a 2.45 to 5% aqueous solution of a strong acid of the 3,81 7 y nnet July 7, 1959 class consisting of sulfuric acid, hydrochloric acid, phos- TH R EN phofic acid, oxalic acid and maleic acid to rednce'dis- I V s coloration and increase the heat stability of said article. 5 gr Textile Research Journali January 1955 2 83. References Cited in the fil of this patent 65 Sgiloutedenz Mellind Textilberichte, January 1957, pp; UNITED STATES PATENTS Q Skinklet American' Dyestufi Reporter, September 23,

2,758,003 Kleiner Aug.- 7, 1955 10 1957, pp. P706-P708. 

1. PROCESS FOR IMPROVING THE DYEABILITY OF SHAPED ARTICLES FORMED FROM A POLYMERIC SUBSTANCE SELECTECD FROM THE GROUP CONSISTING OF CYANOETHYLTED CELLULOSE, POLYACRYLONITIRLE, POLYMERTHACRYLONITRILE, POLYVINYLIDENE CYANIDE, COPOLYMERS MAINLY CONSISTING ESSENACRYLONITRILE AND COPOLYMERS MAINLY CONSISTING ESSENTIALLY OF VINYLIDENE CYANIDE, WHICH COMPRISE THE STEPS OF (1) TREATING SAID ARTICLES FOR 1/2 TO 2 1/2 HOURS IN A SOLUTION CONTAINING FREE HYDROXYLAMINEE IN A CONCENTRATION BETWEEN 0.12 ANS 0.4% AND (2) AFTER THE HYDROXYLAMINE TREATMENT TO OBTAIN FROM ABOUT 0.5 TO 10% CONVERSION OF THE NITRILE GROUPS IN SAID ARTICLE, FURTHER TREATMENT OF SAID ARTICLE WITH A O.16 TO 3% AQUEOUS SOLUTION OF ETHYLENEDIAMINE AT 50-125*C. FOR FROM 1/2 TO 3 1/2 HOURS. 